TWEAKR belongs to the TNF family of transmembrane proteins and contains a cytoplasmic "death domain", which can activated the cell's apoptotic machinery. It is expressed in the spleen, thymus, peripheral blood lymphocytes, colon, and small intestine. Signal transduction by TWEAKR can be activated by either the membrane anchored or the soluble TWEAK. Recombinant soluble TWEAKR is a 53 amino acid polypeptide (5.6 kDa) comprising the entire extracellular domain of the full length TWEAKR protein.